1. Field of the Invention
This invention relates, in general, to a pneumatic manifold for a braking system of a railway vehicle, and more particularly, to a joint seal operative for sealing one or more passageways of a pneumatic manifold for a railway vehicle.
2. Description of the Related Art
Most railway vehicles, such as railway cars and locomotives, are equipped with some form of a pneumatic brake system commonly referred to as air brake systems. Such systems utilize compressed air from an onboard compressor to provide braking power to the wheels of a railway vehicle. Various sizes and configurations of air brake systems may be adapted for a plurality of railway vehicles, including locomotives, freight cars, and passenger cars. Typically, air is stored in a reservoir tank in a compressed state. A plurality of brake lines delivers the compressed air to one or more pneumatic valves, which in turn regulate the air pressure of one or more brake cylinders. By increasing or reducing the pressure in the brake cylinders, brakes are disengaged or engaged, respectively.
Modern air brake systems also include a pneumatic manifold for directing the compressed air between various pneumatic components. The pneumatic manifold typically includes two or more plates having a plurality of ports and passageways provided on their respective interior surfaces. The ports and passageways on each plate are dimensioned such that they correspond to the ports and passageways on an abutting plate. The ports and passageways on the adjoining plates form pneumatic pathways for routing compressed air to various pneumatic devices. Compressed air from a pneumatic source is received inside the manifold and routed through the plurality of ports and passageways to other pneumatic circuits, couplings, and devices. Two or more manifold plates form a manifold section. A plurality of manifold sections may be connected to form a single manifold. The manifold sections are typically connected at their lateral edges.
Air-tight connection between the manifold plates and/or manifold sections is achieved using an adhesive or a gasket. A simple air seal between the adjoining manifold parts is not commonly utilized because of the increased difficulty in servicing the seal once the manifold is installed on a railway vehicle. The adhesive is intended to fill the voids between the plates and/or sections and create an air-tight connection therebetween. A plurality of alignment pins may be provided on the interior surface of one plate to engage a plurality of alignment holes provided on the interior surface of the corresponding plate. Similarly, alignment pins and holes may be provided on the adjoining manifold sections to connect the corresponding ports or passageways. The manifold plates and/or sections may be further secured by fastening means, such as bolts. A common problem with manifolds of such design is that the adhesive sometimes blocks the ports and passageways inside the manifold and thereby creates a reduction in pressure. In some instances, the adhesive may completely block one or more ports or passageways, which leads to an improper operation of the air brake system.
In order to overcome this deficiency, some manifolds include a center plate provided between the two manifold plates. The center plate increases the separation distance between the manifold plates and reduces the possibility that the adhesive used to bond the plates may block the ports and passageways of the manifold. Similarly, the center plate may be provided between the two adjoining manifold sections. The separation between the plates and/or sections increases the capacity of the manifold and usually requires increased pressure to maintain the braking efficiency.
Other manifold designs may include a jumper plate provided on top of two or more adjoining manifold plates and/or sections. The jumper plate includes one or more pneumatic passageways that correspond to the ports or passageways on the manifold. A typical jumper plate requires the compressed air to travel through a tortuous path that inevitably leads to a reduction in operating pressure within the manifold. Additionally, because the jumper plate is provided on top of the manifold, it increases the size and complexity of the manifold. The addition of the jumper plate leads to an increased cost for manufacturing and/or installing the pneumatic manifold.